Recognizing Espresso Blonding: Meaning, timing, and practical application

What is Espresso Blonding?

Blonding refers to the visible lightening of the espresso stream and crema towards the end of extraction. During this phase, the concentration of dissolved substances decreases significantly, the flow becomes thinner, and the flavor is more likely to become bitter or weak. For those who want to confidently answer the question " When to stop brewing espresso?" , blonding serves as a practical, visual indicator.

Visual characteristics: color, crema, flow

Color: The stream changes from nutty-chocolatey to straw-yellow to light yellow. The crema lightens and loses saturation.
Crema: Less structured crema, larger bubbles; the tiger pattern fades.
River: Thin, often fast-flowing; at the end the stream "spindles out" narrowly.

Important: Blonding is normal. The crucial thing is to interpret it correctly and combine it with the target formula.

At what point does one speak of blonding?

Blonding typically begins when the TDS in the stream drops and the extractable compounds in the puck are depleted. The timing varies depending on the beans, roast level, and recipe.

Time, ratio and yield : practical guidelines

Classic espresso (1:2 espresso shot ratio ): 18 g in, approx. 36 g out in 25–30 seconds from pump start. Blonding typically begins shortly before the target yield.
Ristretto (1:1.5–1:1.8): Blonding often only begins after the target yield; taste controls the stop signal.
Lungo (1:2.5–1:3): Blonding starts well before the target yield; high risk that the lungo may become bitter .

Practical tip: Primarily base your stop signal on the ratio/yield and use blonding as a safety margin to avoid over-extraction. Observe the espresso extraction: color and flow (i.e., espresso extraction color ) are your live indicators.

Differences due to roast level, bean age and water

Roast level: Lighter roasts bleach earlier and lighter; dark roasts later and more slowly.
Bean age: Very fresh beans (< 7 days) produce more foam, blonding appears "hidden". Older beans blond abruptly and earlier.
Water: High carbonate hardness/alkalinity buffers acidity and can make the blonding transition appear softer. Soft water often shows clearer edges.

Blonding recognizes two espresso cups with espresso in close-up.

Why pay attention to blonding?

Blonding is not a mistake, but a helpful marker. It shows when the shot loses its "carrying" quality and the solvent profile begins to change.

Taste, consistency and reproducibility

Taste: After blonding, the likelihood of bitter, woody notes and a thinner cup increases.
Consistency: Stopping at the blonding stage reduces variation between shots, especially when using different beans.
Workflow: A visual stop signal complements the timer and scale to form a robust triad.

Using blonding in practice: step-by-step

Setup, light and bottomless portafilter

Even light from the front/above, no harsh shadows. Use the light-colored side of the mug for contrast.
Bottomless portafilter: Makes flow pattern, channeling vs blonding and color changes immediately visible.
Clean spout (for portafilters with spouts) and light, matte surface for better color recognition.

Shot Guide: Start, Observe, Stop

Start: Pump on. Thick, dark syrup, first tiger stripes.
Observe: Color and flow stabilize, crema is rich and fine.
Blonding zone: The ray visibly brightens, the crema becomes paler, and the flow accelerates slightly.
Stop: Ideally, shortly before or at the beginning of blonding, once the ratio/yield has been reached.

If you haven't reached the desired ratio yet , but strong blonding is occurring, the grinder/dose is usually incorrect – see causes.

Stopping after Blonding vs. Timer vs. Brew Ratio

Stop after blonding: Intuitively and by touch. Works well if you have good visual training.
Timer: Constant brewing time as a guideline. Can be misleading when changing beans.
Brew ratio : Most reproducible (scales under cup). Blonding serves as a corrective to avoid overdoing it.

Best practice: Use ratio as the main goal, a timer as an early warning system, and blonding as a stop signal. This is how you combine measurability and sensor technology.

Cups in a portafilter machine. Espresso flows into a cup.

Common causes of premature blonding and solutions

Grind size, dose, distribution and tamping

Grind too coarse: Adjust to a finer setting until the desired ratio is reached in 25–30 seconds.
Dose too low: Increase by 0.5–1 g (taking sieve size into account) to support the puck.
Distribution: Use WDT or a leveler; remove clumps and distribute evenly.
Tamping: Straight, with even pressure; wipe the edge clean to avoid side channels.

Temperature, pressure profile and flow restrictions

Temperature too low: Increase by 1–2 °C, especially for light roasts.
Pressure profile: A short pre-infusion section stabilizes the puck, reduces channeling .
Flow: Excessive flow (e.g., from a wide nozzle) can destabilize the puck. Slight restriction helps.

Bean freshness, roast level and water quality

Freshness: Often most stable 7–30 days after roasting; very fresh can be deceptive, very old bleaches early.
Roast level: Light beans require a finer, hotter, often longer contact time; dark beans require a shorter and cooler time.
Water: Target alkalinity 50–80 mg/l, total hardness 80–150 mg/l. Too soft: bland; too hard: bitter/musty.

Blonding vs. Channeling vs. Tiger Striping

Blonding is a smooth, gradual lightening of the entire stream. Channeling shows uneven, light jets, side spraying, or holes in the flow; the cup tastes thin, sharply acidic, or bitter. Tiger striping (dark/light streaks) is a normal pattern in the mid-phase and not a fault. Don't automatically confuse "light" with channeling : the key is the evenness of the entire stream.

Tamper, espresso cup and portafilter filled with coffee grounds

Quick checklist and recommended tools

Before the shot: Measure the sieve appropriately, grind fresh, distribute cleanly ( WDT ), tamp evenly.
Observe: color, crema, flow; run ratio and time.
Stop: At the ratio target and at the latest at the start of blonding.
Adjust: Grind finer or increase the dose if blonding starts before the target yield.
Tools: Bottomless portafilter, precision scale with timer, uniform lighting, WDT tool, leveler, tamper, water filter/cartridge.

Next steps: Keep a short shot log (bean, date, grind, ratio, time, blonding note). This will help you identify patterns and find the sweet spots faster. #staywild